1. Field of the Invention
This invention pertains generally to communications antennas, and more particularly to dual-band and multi-band antennas formed from composite right/left-handed transmission lines.
2. Description of Related Art
To satisfy the demands of compact and versatile wireless communication systems, a compact and dual-band and multi-band antenna is desirable. Antennas of this nature are required in various wireless systems, such as GSM/DCS cellular communication systems, and synthetic aperture radar (SAR) systems. Traditional dual-band antennas have been implemented by modifying a conventional microstrip patch antenna by operating it at different harmonics, adding an additional resonator, or by reactively loading the patch antenna with shorting pins. These antennas function at two different frequencies but have similar radiation patterns at each frequency. These dual-band methods have additional drawbacks, including that the operational frequencies are limited to integer multiples of the fundamental mode by operating at different harmonics, while the physical size requirement increases when adding another resonator. In the case of reactive loading, the placement and the number of required shorting pins is not easily determined.
Accordingly, a need exists for a system and method of creating compact dual-band and multi-band antennas which are not subject to the size, pattern and operational limits of conventional antenna radiators. These needs and others are met within the present invention, which overcomes the deficiencies of previously developed antenna system and methods.